The invention relates to a device for heating a yarn in motion, especially a synthetic yarn while being textured by false twisting.
In the description which follows, the conventional expression of "oven" will be employed to denote such a device which, of course, can be employed equally well for treating continuous, mono- or multifilamentary yarns and spun fibers.
Furthermore, the invention will be described as applied more particularly to texturing by false twisting, but it is obvious that this is not limiting and that it can also find applications in other fields, and in general in all cases where it is desired to heat-treat, with precision, yarns traveling at a high speed.
The invention relates more particularly to an improvement made to the ovens described in European Patent Application published under No. 524,111 (patent which corresponds to U.S. Pat. No. 5,193,293).
In the abovementioned European patent application the Applicant Company has described, as follows from the attached FIG. 1 which is a reproduction of FIG. 7 of that document, a new type of oven capable of being employed especially during a drawing-texturing operation, and which consists of an insulating enclosure which surrounds a heater block with which it defines an outwardly open lengthwise channel, inside which the yarn to be treated runs, means for guiding said yarn being provided to ensure its positioning inside said channel.
The embodiment illustrated in FIG. 1 enables two yarns (5) to be treated simultaneously in parallel. The heater block consists of a unit which comprises at least two cylindrical sections (A, B) which have different diameters and are arranged one extending the other, guiding means (rings 1, 3, 4) for the yarns being provided along the heater block so that they are kept at a constant distance from the surface of the cylinder (A) of small diameter, so that its temperature rise is obtained in this region by radiation and so that it comes into contact with the surface of the zone (B) of large diameter, the transmission of heating being then produced by contact or conduction.
When compared with the conventional ovens in which the heating of said yarn in motion is obtained by means of a heating liquid which, on evaporating, transmits its heat to a body with which the yarn is directly in contact (see especially French Patent 2,619,128), such a solution makes it possible to produce units of particularly simple design permitting the production of heat exchanges which are adapted as a function of the treatments, for example having a slow and uniform rise in bringing the yarn up to temperature, followed by a greater thermal shock, or combining such stages in a different manner; it also permits very high yarn running speeds inside the oven, the heat exchange being produced very uniformly, the risks of vibrations (and therefore of nonuniformity in the treatment) being practically completely eliminated and the placing of the yarn inside the oven being made easier.
Now there has been found--and this is what forms the subject of the present invention--an improvement made to the design of such ovens which makes them easier to maintain (cleaning, changing elements) and which also makes it possible to carry out rapidly and without any difficulty the replacement of a given heating element with another which is adapted as a function of the treatment to be carried out, thus making it possible, if desired, to adapt a machine as a function of the various types of yarns to be treated, given that it is well known that the heat treatment conditions may vary as a function of the nature of said yarns.